The present invention relates to a method of manufacturing a chip carrier which carries an integrated circuit semiconductor chip (IC chip) in an enclosure of an insulating material such as plastics and ceramics. In more particular, the present invention relates to a method of shaping leads protruded from lateral sides of the chip carrier enclosure into the form of the letter "J".
The method of forming the J-shaped leads in a prior art chip carrier comprises cutting the straight leads protruded from the lateral sides of the enclosure at a predetermined length and bending the leads downward at an angle of about 45 degrees by use of a punch at an upper position and a die at a lower position. The bent leads are further bent vertically by a punch, followed by being curled to bring the end of lead into a position facing the bottom of the enclosure by using a punch which depresses the leads and a curling die having a half-circled trench which receives the depressed leads.
The prior art method relies only upon forces in the vertical direction applied by the punches and dies. Therefore, a plated layer on the surface of leads is apt to be shaved off. Moreover, in the final curling process, the curling die having the half-circular trench is positioned under the processed chip carrier. Therefore, the shaved wastes of the plated layer and wastes of plastic material removed from the enclosure at the roots of the leads fall into the trench and accumulated on the bottom of the trench. Consequently, the wastes are embedded into the surface of the leads which are processed with the curling die. The wastes of the plated layer attached to the leads would cause short-circuit between leads, and the plastic wastes embedded in the surface of the leads would prevent good expansion of a solder over the surface of the leads when the leads of the plastic chip carrier is soldered to a printed circuit board.